Product idea: SCART auto switch box with built in RGB -> Component converter

[viletim]

That 'RGB the easy way' and other related topics has me thinking...

An automatic SCART switch box with a built in RGB to component video converter buit in would be a good idea. It would also have an adjustable gain RGB output for use as an arcade monitor video amplifier.



One of these could be gutted and circuitry installed. There would be:

• Three auto switching RGB SCART inputs (composite, component, and s-video would also be passed through to the SCART out)
• One SCART output
• One set of component outputs by three RCA/Phono sockets
• Stereo audio output (phono sockets again)
• One more RGB output which would be wired in parallel with the SCART out but will go to a 'wire push connector' (like the type found on the back of cheap stereo systems to connect speakers). This would be handy when you have a monitor with an unusual connector: just fund a cable which is half right, cut it up and connect the bare wires to the switch box

It's just an idea. I could produce and sell something like this but I'm skeptical and don't think there'd be enough interest to make it worthwile.

[Raskolnikov]

That 'RGB the easy way' and other related topics has me thinking...

An automatic SCART switch box with a built in RGB to component video converter buit in would be a good idea. It would also have an adjustable gain RGB output for use as an arcade monitor video amplifier.



One of these could be gutted and circuitry installed. There would be:

• Three auto switching RGB SCART inputs (composite, component, and s-video would also be passed through to the SCART out)
• One SCART output
• One set of component outputs by three RCA/Phono sockets
• Stereo audio output (phono sockets again)
• One more RGB output which would be wired in parallel with the SCART out but will go to a 'wire push connector' (like the type found on the back of cheap stereo systems to connect speakers). This would be handy when you have a monitor with an unusual connector: just fund a cable which is half right, cut it up and connect the bare wires to the switch box

It's just an idea. I could produce and sell something like this but I'm skeptical and don't think there'd be enough interest to make it worthwile.

Oh, it would definitely be worthwhile to me if this could happen. It would definitely save me money as I will probably end up needing to buy both of those things.

[Drewman21]

I think it is a huge idea. The only two things you would need to do the first being is to market it to the right people to make it sell. So i mean to the old school gamers and home arcade gamers. So secondly you may want/have to sell cables to go with it to make it work with different systems and maybe arcade boards jamma or not. Or at least adapt to jamma for the video out.
As for the scart output it would be nice to have the options of phono jacks or at least to toggle between the two. I'd go for it man!

[viletim]

I think it is a huge idea. The only two things you would need to do the first being is to market it to the right people to make it sell. So i mean to the old school gamers and home arcade gamers.

This would be more of a small scale afair. 50 units, something like that. Spamming a few message boards is about as close as I'm willing to get to the sordid world of marketing/advertising.

So secondly you may want/have to sell cables to go with it to make it work with different systems and maybe arcade boards jamma or not. Or at least adapt to jamma for the video out.

Cheap SCART cables for every console are readily available online from what I can see.

JAMMA is too loose a standard to implement directly, it gets dodgy with stereo sound, etc. But I think an arcade video input would be a handy addition. Not directly through a JAMMA harness (I don't need all those power and control lines runing through the box), but maybe a molex cable or something for just video/sound. Arcade people are used to making their own cables/harnesses anyway arn't they?

As for the scart output it would be nice to have the options of phono jacks or at least to toggle between the two. I'd go for it man!

Yeah, I think you're right. Instead of more sockets on the unit, I reckon a cheap svideo/composite -> SCART adaptor could be rewired/modified to become a SCART -> RGB + video (phono) adaptor. I could output a TTL composite sync on one of the useless SCART data lines (pins 10 and 12) and let the input/output switch become a c-video/c-sync switch.

BTW, anyone read the Wikipedia entry on SCART? Somebody has cleaned up that mess and made a good, informative article.

[ken_cinder]

Arcade people are used to making their own cables/harnesses anyway arn't they?

Yes, we certainly are. I have several Jamma harness, a couple of which are wired custom for wierd applications (Hooking up to my HDTV via VGA for instance). Custom VGA harnesses for my arcade monitors (MAME anyone?) that use 6 pin molex, and a few other strange wiring concoctions.

[viletim]

I've decided to go ahead with this. Here's the spec:

4 INPUTS
1 Arcade video (high-Z, adjustable gain) by 10 pin IDC connector.
3 RGB SCART
Input is automatically selected by sync detection

3 OUTPUTS
1 Arcade video (fixed gain) by another 10 pin IDC connector.
1 Component video by 3 RCA.
1 RGB SCART (will also pass through composite vid & s-vid on SCART inputs)
6 RCA connectors wired in parallel with the SCART for red, green, blue, c-video (or c-sync, switchable), left audio, right audio.

The three different output types (arcade/component/SCART) are independent so it's possible to drive three displays at once.

Also has horiz centre adjustment to compensate for RGB SCART shift on crap TVs.

No support for high definition, or anything other that standard ~15Khz video. No support for any kind of component video input (I can't see the point).

High build quality! I've already sourced some heavy duty metal cases for them. And I'm currently in the process of sourcing all the components. But I though I'd just post this in case I'd left out something obvious.

[Drewman21]

Sweet deal that you are going through with this. I have 3 suggestions if your intrested. The first being that maybe offer up 2 types of enclosure types. One that is for lack of a better term "left out" on the table top for people that switch stuff all the time like the image of the box that you posted at the top The other type could be more of a AV component type. Something that fits the AV rack or home component gear like the http://images.google.com/imgres?imgurl=http://www.krunker.com/wp-content/uploads/2008/04/066-thumb.jpg&imgrefurl=http://www.krunker.com/2008/04/20/psyclone-hdmi-selector-model-psc47-review/&h=304&w=454&sz=40&hl=en&start=4&um=1&usg=__kJtm4oeL1Biw16MNF9YObjx0zJg=&tbnid=cRi_QhpSh2lSYM:&tbnh=86&tbnw=128&prev=/images%3Fq%3Dpsyclone%2Bswitcher%26um%3D1%26hl%3Den%26safe%3Doff%26client%3Dsafari%26rls%3Den-us%26sa%3DNr. I was going to do this with my Jrok rgb to component box and put it into this http://www.pactecenclosures.com/Plastic-Enclosures/RM-178.html.

2nd suggestion is put the power supply, if it needs one, on the inside. I hate wallwarts and power jacks kinda suck on them. And my last suggestion would be to add a switch for the arcade input side for the audio to drop the amplified sound down to line level or just close to. Could be done with a mini switch on the bottom.
Any ways thats my two cents. Can't wait to see it and or at least a mock up(Hint Hint!)

[ken_cinder]

Drewman21, nice catch there on the arcade audio. I don't own, nor have I ever owned an arcade PCB that doesn't output amped audio already.

The only solution I've found for taking this and making it useable at line level is resistors in series on the lines. Probably not the best way of doing it, but it "works".
A Line Output Converter would be best, but I don't know about the added cost to this project for adding something that does the job properly like a $30-$80 commercial solution would.

But if you're going to aim at supporting arcade input/output, it would probably be best to do this. Advanced users may otherwise do the job themselves, but novices would probably buy it for ease of use if this was implemented (And they won't go blowing up their amps/receivers with speaker level signals.........though that's their fault anyway)

[Drewman21]

One more suggestion i would offer up. A LM1881 in line wouldn't hurt either to help with the sync on some machines/boards.

IJTF thanks for the nod. For most arcade boards people are going to have to make their own power/jamma edge type connector anyways. There is no good standard after JAMMA
for other boards.

Once again its just a thought I had.

[ken_cinder]

viletim, or someone else could make jamma connectors suited to use with this. Proper video connector to it and audio cables.
I'd go with seperate ports for line output converted audio, and you know what? This would also make it feasible to use things like portables that have been modified for video output, but most people usually add their own audio lines as well, but if not.......

I'm an administrator at 1emulation.com where we have many members who own arcade hardware and consoles with personal modifications, I'm sure plenty would be interested in this if the price is right.
Hell I'd be interested if I can wire up a VGA cable to it, and the line output converter was built in. Right now, playing arcade games on my LCD TV's is done via hack job cables.
My Versus City cabinet runs a MAME box, and switching out my harness' to put my actual arcade boards in is a HUGE pain in the ass, an "easy box" for me would be awesome, as my current setup is messy.

[viletim]

Drewman21,

Good suggestions. As I'm gutting an already existing product for the enclosure  (and there's no way I'm cutting SCART shaped holes into plastic boxes) I'm a bit limited to what I can choose from. I went withthis one. See those muchanical switches? They'll go, and in their place will live phono sockets on one side for component. On the other side will be two IDC (like what computer drives use) sockets for arcade in/out.

There's not enough room in the case for a power supply, it'll have to be external. I don't like the wall adaptors much either but there isn't much I can do about it here.

Arcade audio is attenuated, yes. Audio out is line level only.

Here's a diagram which should give you an idea of how it'll work.

I think I'll keep the device as versatile as possible and leave Jamma integration up to the user. You've still got to work out how the controls are wired up.

Oh, and IJTF_Cinder, could you tell me how stereo sound works on Jamma boards when there's only one speaker output?

Edit - links fixed.

[STB]

Both of your links are not working.
Can you update them.


For modern gaming/video equipment it would be niche to have S/PDIF routing to the SCART connector.

STB

[viletim]

STB,

Fixed them!

S/PDIF over SCART? That's very wierd sounding... I can't even find any info on it. Can you explain how it works? Do any game consoles do this?

I want to focus on support for game consoles rather than other A/V stuff like DVD players, etc. One thing that comes to mind atm is that there will also be no 14:9 switching. This is because lots of game consoles send the 14:9 switching signal instead of the 4:3 one due to technical limitations. So any voltage on the SCART switch line (pin8) would be turned into a 12V 4:3 signal at the output.

[STB]

You misunderstood. Besides the SCART connector a S/PD connector IF has to be added. E.g. Sony's PS2 & 3 both have S/PDIF Audio output.

In other words, SCART1..SCART3 need additional S/PDIF Inputs and the SCART output an additional S/PDIF output connector.

If you want to use the LM1881 only for SYNC stripping a simple TL082 Opamp with some passives can do this a lot of cheaper. If you are interested send a PM.

If i understood your block level diagram right. You first amplify the video signals from the SCART Inputs an then except for the ARCADE output you attenuate them.This will introduce noise in those signals which will decrease picture quality on these outputs. It might be a better way to route them in two seperate pathes to avoide amplifying and attenuation.


STB

[viletim]

You misunderstood. Besides the SCART connector a S/PD connector IF has to be added. E.g. Sony's PS2 & 3 both have S/PDIF Audio output.

In other words, SCART1..SCART3 need additional S/PDIF Inputs and the SCART output an additional S/PDIF output connector.

Fair point... I'm not much of a fan of digital audio but I'll consider it.

If you want to use the LM1881 only for SYNC stripping a simple TL082 Opamp with some passives can do this a lot of cheaper. If you are interested send a PM.

I'm sticking with the LM this time. I need the back porch output too.

If i understood your block level diagram right. You first amplify the video signals from the SCART Inputs an then except for the ARCADE output you attenuate them.This will introduce noise in those signals which will decrease picture quality on these outputs. It might be a better way to route them in two seperate pathes to avoide amplifying and attenuation.

You understand correctly. Yes, it's a bit of a compromise. You see, the Amp&Clamp block is a TLS1233. The RGB to YCrCb matrix relies on the clamp in the TLS so it must come after. I'll upload a preliminary circuit diagram in a few days.

[ken_cinder]

It depends viletim. My Taito F3 has an AUX header for stereo audio that requires a custom cable, some boards use a second set of pins on the jamma connector itself.
In general, wherever it comes from, it's nothing more than another pair of wires. Most boards I have seen though, make use of an AUX harness.

In the case where stereo audio is found on the jamma edge connector itself, you'll find + and - are infact + on both sides for each speaker, where you will need to wire the - on each speaker to ground. Still, just a case of "some wires" and if not wired up properly, you'll get faint audio or simply noise.

[rtw]

for viletim,

If an arcade cabinet is wired as JAMMA it has only one speaker there are no exceptions.

In order to get stereo an extra connector is used on the PCB itself. This signal is fed directly to the stereo speaker harness. In my cabinet I have two speakers each one 4 ohm. In MONO mode I wire them in series.

On the newer JVS cabinets (NAOMI) the unamplified sound is taken from the PCB via phono jacks and fed to a stereo amplifier in the cabinet.

I recently tried to connect my PS2 via SCART to my intervideo arcade monitor. It works but the picture is dim. Today I found your excellent page where you design the "AC coupled video amplifier" . I would be very interested in this project but I was wondering if you would consider building a single module with a clamp and amp. I'm using the Ultimarc JPAC in my cabinet and all I really need is the amplification circuit to get things 100%. I know quite a few people who would be interested in such an SCART2ARCADE module.

rtw

[undamned]

Although it's not an autodetect solution, I'm surprised that nobody uses (that I've seen) those ginormous server KVM switches.  It'll switch high definition analog up to 16 channels in and one out.  All you need is a keyboard (or a hacked keyboard device w/ a select button) to switch between sources.  Find me a 16 channel high definition video switch anywhere else for a hundred bucks.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310087265947
-ud

[RGB32E]

@viletim
Do you think you'll be able to build a better RGBS to Component converter than the Cypress CYP-2100 unit or the Kramer FC-14?

[viletim]

rtw,
During my research for this little project, I discovered the TLS1233 which makes a very neat video preamp. I'll publish a new AC Coupled Video Amp based around this IC (which seems to be easily obtainable is most countries). It'll have a single contrast control for all three video channels, half the component count, and a much simpler power supply (just +12v) than the old circuit. I may ba able provide kits or prebuilt boards, I'll see....

undamned,
Yup, it looks like a bargain if you need a huge 75 ohm distribtuion amplifier! Not much good for arcade monitors though.

RGB32E,
What, exactly, is wrong with those two (other than the price)? RGB -> Component isn't too tricky provided you don't need it to work with > 15.7KHz horiz sync rates. There's a good circuit on elm-chan.org. Maybe some cheap kits of a similar circuit would be a good idea...?


In any case, I'm very busy till the end of November. All my current projects are on hold for the moment.

[rtw]

@viletim,

rtw,
During my research for this little project, I discovered the TLS1233 which makes a very neat video preamp. I'll publish a new AC Coupled Video Amp based around this IC (which seems to be easily obtainable is most countries). It'll have a single contrast control for all three video channels, half the component count, and a much simpler power supply (just +12v) than the old circuit. I may ba able provide kits or prebuilt boards, I'll see....

[Sorry for the late reply, didn't get the notifier email...]

That sounds very interesting specially the simple part Prebuilt sounds even better! I had a quick look at the data sheet and it seems to fit the job perfectly. Looking forwards to the circuit diagram with anticipation.

rtw

[RGB32E]

During my research for this little project, I discovered the TLS1233 which makes a very neat video preamp. I'll publish a new AC Coupled Video Amp based around this IC (which seems to be easily obtainable is most countries). It'll have a single contrast control for all three video channels, half the component count, and a much simpler power supply (just +12v) than the old circuit. I may ba able provide kits or prebuilt boards, I'll see....

Do you think that the TLS1233 would make a suitable video preamp for the TG16 systems?  I checked out the datasheet for this IC and the brightness/contrast controls look promising!  So, its just a matter feeding the clamp/burst output from a LM1881 (or equivalent) to the TLS1233 and adding the required external components?  Sounds fun!

[viletim]

Do you think that the TLS1233 would make a suitable video preamp for the TG16 systems?  I checked out the datasheet for this IC and the brightness/contrast controls look promising!  So, its just a matter feeding the clamp/burst output from a LM1881 (or equivalent) to the TLS1233 and adding the required external components?  Sounds fun!

It makes a good general purpose amplifier with lots of features but it's not really well suited for a video driver where large output swings, variable gain, and clamper are not required. A video grade opamp and a few resistors should be all that's required for the TG16 (that's the same hardware as the PC Engine, right?)

Something like this (I drew this one up a while ago, but don't have a PCE/TG16 to try it) with 2 of MAX4451 would be more suitable for a fixed modification:

Code Select Expand

.  Amplifier x3
.       
.        470    470
.   +----RRR-+--RRR--+
.   |        |       |
.  ---GND    | |\    |
.            +-|-\   |   75
.      10u     |  >--+--RRR--o video out
.Vid --CCC---+-|+/
.in    +     | |/
.            R
.            R 8k2
.            R
.            |
.   Vref-----+     
.
.
.  Bias voltage
.         ________________________VCC +5v
.          |                    |
.          |                    |
.          |                    |
.          |                    |
.          |                    |
.          R     10k         | /c  NPN     
.     1k   R<----RRR-----+---|<
.    pot   R             |   | \e
.          |             R      +-----Vref
.          |        10k  R      R
.          |             R      R 1k
.          |             |      R
.          |             |      |
.        -------------------------GND


An amp based around the TLS1233 would need to be powered by an external power supply (it requires 12V at ~200mA). Maybe make a good general purpose experementer's video amp...